In the process of shipping an item from one location to another, a protective packaging material is typically placed in the shipping container to fill any voids and/or to cushion the item during the shipping process. Some commonly used protective packaging materials are plastic foam peanuts and plastic bubble pack. While these conventional plastic materials seem to perform adequately as cushioning products, they are not without disadvantages. Perhaps the most serious drawback of plastic bubble wrap and/or plastic foam peanuts is their effect on our environment. Quite simply, these plastic packaging materials are not biodegradable and thus they cannot avoid further multiplying our planet's already critical waste disposal problems. The non-biodegradability of these packaging materials has become increasingly important in light of many industries adopting more progressive policies in terms of environmental responsibility.
These and other disadvantages of conventional plastic packaging materials have made paper protective packaging material a very popular alterative. Paper is biodegradable, recyclable and renewable; making it an environmentally responsible choice for conscientious companies.
While paper in sheet form could possibly be used as a protective packaging material, it is usually preferable to convert the sheets of paper into a low density cushioning product. This conversion may be accomplished by a cushioning conversion machine, such as those disclosed in U.S. Pat. Nos. 4,026,198; 4,085,662; 4,109,040; 4,237,776; 4,557,716; 4,650,456; 4,717,613; 4,750,896; and 4,968,291. (These patents are all assigned to the assignee of the present invention and their entire disclosures are hereby incorporated by reference.) Such a cushioning conversion machine converts sheet-like stock material, such as paper in multi-ply form, into low density cushioning pads.
A cushioning conversion machine, such as those disclosed in the above-identified patents, may include a stock supply assembly, a forming assembly, a gear assembly, and a cutting assembly, all of which are mounted on the machine's frame. During operation of such a cushioning conversion machine, the stock supply assembly supplies the stock material to the forming assembly. The forming assembly causes inward rolling of the lateral edges of the sheet-like stock material to form a continuous strip having lateral pillow-like portions and a thin central band. The gear assembly pulls the stock material through the machine and also coins the central band of the continuous strip to form a coined strip. The coined strip travels downstream to the cutting assembly which cuts the coined strip into pads of a desired length. Typically, the cut pads are discharged to a transitional zone and then, either immediately or at a later time, inserted into a container for cushioning purposes.
With particular reference to the gear assembly, it includes loosely meshed gears between which the unconnected strip travels. The drive gear is fixedly mounted to a rotating shaft which is coupled to a motor. During operation of the machine, the gear motor rotates the shaft (and thus the drive gear) in an appropriate direction whereby the central band of the strip is grabbed by the gear teeth and pulled downstream through the nips of the gears. Thus, the gear assembly is a rotating conversion assembly which determines the production rate of the coined strip and, therefore, the cushioning products, or pads. (This "grabbing" simultaneously coins the layers of the central band together to form the coined strip.)
By selectively controlling the gear assembly (i.e., by activating/deactivating its motor) and the cutting assembly, a cushioning conversion machine can create pads of a variety of lengths. This feature is important because it allows a single machine to satisfy a wide range of cushioning needs. For example, relatively short pad lengths can be employed in connection with small and/or unbreakable articles, while longer pad lengths can be employed in connection with larger and/or fragile articles. Moreover, a set of pads (either of the same or different lengths) can be employed in connection with uniquely shaped and/or delicate articles, such as electronic equipment.
Presently, a variety of length-controlling systems are used to control pad length. For example, a manual system is available in which a packaging person manually activates the gear assembly (i.e., steps on a foot pedal) for a time period sufficient to produce a coined strip of the desired length. He/she then manually deactivates the gear assembly (i.e., releases the foot pedal) and activates the cutting assembly (i.e., pushes an appropriate button on the machine's control panel) to cut the coined strip. In this manner, a pad of the desired length is created. Alternatively, the system is designed so that a manual deactivation of the gear assembly (i.e., release of the foot pedal) automatically activates the cutting assembly.
Another technique used to control pad length is a time-repeat system. In such a length-controlling system, a timer is electrically connected to the gear assembly. The timer is set for a period (i.e., seconds) which, based on an estimated gear velocity, corresponds to the desired length of the pad. The time-repeat system is designed to automatically activate the gear assembly for the selected period and thereby, assuming the estimated gear velocity is correct and constant, produce a coined strip of the desired length. The system then deactivates the gear assembly and activates the cutting assembly to cut the coined strip into a first pad of the desired length. Thereafter, the system automatically re-activates the gear assembly to repeat the cycle so that, if the timer has not been reset, a multitude of pads of substantially the same length are continuously created.
A further available length-controlling system is a removal-triggered system. This system is similar to the time-repeat system in that it deactivates the gear assembly based on the setting of a timer. However, with the removal-triggered system, the gear assembly is not automatically reactivated. Instead, it is only re-activated when the cut pad is removed, either manually by the packaging person or mechanically by a conveyor. Upon reactivation, another pad of the same length is produced unless the timer is reset.
Yet another length-controlling system includes a length-selection system which allows a packaging person to select certain predetermined pad lengths. In such a system, a selection panel (e.g., a key pad) is provided with a plurality of length options (e.g., buttons) so that a packaging person can manually select the appropriate pad length. When a particular length option is selected, the gear assembly is automatically activated for a period of time (based on estimated gear velocity) corresponding to the selected pad length. At the expiration of this time period, the gear assembly is deactivated, and the cutter assembly is activated. The process is then repeated and, unless another length option is manually selected, a subsequent pad of the same length is produced.
In many packaging situations, the production of a single pad length is sufficient to satisfy cushioning requirements and the above-discussed automatic controlling systems are usually compatible with these situations. For example, with a time-repeat system and/or a removal-triggered system, the packaging person manually sets the timer at a period corresponding to the desired length and a plurality of pads of this length are produced. Likewise, with a length-selection system, the packaging person manually selects the desired length option and a plurality of pads of the selected length are produced.
In other packaging situations, however, single pad length production is insufficient to satisfy cushioning requirements. For example, a series of identical packaging jobs may each require a set of pads of different lengths. Alternatively, a series of widely varying packaging jobs may each require a single pad, but each job may need different sized pad. Also, a series of non-identical packaging jobs may each require a different set of pads of varying lengths.
The non-manual length controlling systems sometimes do not adequately accommodate these latter packaging situations. Specifically, in order to sequentially produce pads of different lengths, the timer on a time-repeat systems and/or a removal-triggered system must be manually reset after each pad. Likewise, if a length-selection system is used, the packaging person must continuously manually change the length option. Thus, a high degree of interaction with the cushioning conversion machine is necessary. Therefore, in order for a packaging person to properly interact with the machine, at least minimal training is necessary. Additionally, while the packaging person is interacting with the machine, he/she is not packaging thereby hindering the overall efficiency of the packaging program.
Regarding the manual length-controlling system, it can certainly be used to sequentially produce pads of different lengths. However, again, a high degree of interaction is necessary thereby requiring trained personnel and/or thereby hindering efficiency. Moreover, in both the manual and non-manual length-controlling systems, the packaging person must determine (either by experience or experiment) the appropriate pad length. For this additional reason, the use of untrained workers in sophisticated packaging situations is often impractical.
Accordingly, applicant appreciated that a more sophisticated packaging program was necessary to accommodate a full range of packaging situations, especially if untrained workers were to be used as packaging personnel. Additionally, applicant appreciated that a suitable program would automatically determine the cushioning needs of a certain box and would then automatically control the cushioning conversion machine to produce one or more pads of the appropriate length. With such a program, interaction (and thus training) would be minimal even with a series of non-identical packaging jobs which each require a different set of pads of varying lengths. Moreover, in even the simplest of packaging situations (i.e., a single pad length situation) the pads for a particular box could be produced while the packaging person is packing the previous box thereby maximizing efficiency.
Applicant further appreciated that such a sophisticated packaging program could be accomplished with a process controller which, based on the packaging needs of a certain box, would control the gear assembly and the cutting assembly to produce pads of an appropriate length. In order to accomplish this control, however, the process controller needed to receive dimensional data (i.e., length measurements) so that the control of the gear assembly and/or the cutting assembly could be properly coordinated.
Applicant therefore developed the length measuring device of the present invention. The length measuring device may be used in conjunction with a process controller to create a sophisticated packaging program. Specifically, the process controller could automatically determine the cushioning needs of a certain box and then, based on length measurements supplied by the length measuring device, automatically control the cushioning conversion machine to produce a cushioning product of the appropriate length.
More particularly, the present invention provides a cushioning conversion machine comprising conversion assemblies which convert a stock material into a cushioning product and a length measuring device which measures the length of the cushioning product as it is being produced. The conversion assemblies include a rotating conversion assembly and the angular movement of this assembly directly corresponds to the length of the cushioning product. In the preferred embodiment, the gear assembly is the rotating conversion assembly.
The length measuring device is positioned to monitor the angular movement of the rotating conversion assembly and thus the length of the cushioning products. Preferably, the length measuring device includes a rotating member and a monitor. The rotating member is attached to, and rotates with, the rotating conversion assembly and may comprise a disk with a series of openings arranged in equal circumferential increments. The monitor is positioned to monitor the angular motion of the rotating member (and thus the rotating conversion assembly) and it includes a photo-optic transmitter/receiver and a reflector. The transmitter/receiver is situated so that, as the rotating member turns, transmitted light beams will travel through its openings. The reflector is positioned to receive transmitted light beams which travel through the openings and to reflect these transmitted light beams back through the openings.
Thus, applicant's length measuring device is specifically designed to accommodate a sophisticates packaging program. Moreover, applicant's invention provides certain advantages over time-dependent systems, regardless of the sophistication of a packaging program. Specifically, in time-dependent systems, determinations are based on an estimated gear velocity. However, gear velocity has been known to deviate over the course of pad production, due to motor start-up lags, variations in stock material, the different strip profiles, and other factors. With applicant's length measuring device, these factors are irrelevant because determinations are based on the actual angular movement of the gear assembly.